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Background Black screen fly round (BFR) is a mobile sampling method for Glossina morsitans. This technique relies on the ability of operator(s) to capture flies landing on the screen with hand nets. In this study, we aimed to evaluate a vehicle-mounted sticky panel trap (VST) that is independent of the operator’s ability to capture flies against BFR, for effective and rapid sampling of G. m. morsitans Westwood and G. m. centralis Machado. We also determined the influence of the VST colour (all-blue, all-black or 1:1 blue-black), orientation and presence of odour attractants on tsetse catch. Methodology/Principal findings Using randomised block design experiments conducted in Zambia, we compared and modelled the number of tsetse flies caught in the treatment arms using negative binomial regression. There were no significant differences in the catch indices of the three colour designs and for in-line or transversely oriented panels for both subspecies (P > 0.05). When baited with butanone and 1-octen-3-ol, VST caught 1.38 (1.11–1.72; P < 0.01) times more G. m. centralis flies than the un-baited trap. Attractants did not significantly increase the VST catch index for G. m. morsitans (P > 0.05). Overall, the VST caught 2.42 (1.91–3.10; P < 0.001) and 2.60 (1.50–3.21; P < 0.001) times more G. m. centralis and G. m. morsitans respectively, than the BFR. The VST and BFR took 10 and 35 min respectively to cover a 1 km transect. Conclusion/Significance The VST is several times more effective for sampling G. m. morsitans and G. m. centralis than the BFR and we recommend its use as an alternative sampling tool., Author summary The fly round is a mobile method used to sample G. m. morsitans and G. m. centralis, important vectors of human and animal African trypanosomiasis. However, its effectiveness is largely dependent on the skill and ability of the operator(s) to catch flies using a hand net. Here, we report the evaluation of an alternative mobile sampling tool, the vehicle-mounted sticky trap (VST) which is independent of operator skill and ability to catch flies. We show that VST is more effective in catching both female and male G. m. morsitans and G. m. centralis compared to the black-screen fly round (BFR). Furthermore, VST covered the same distance of BFR in a much shorter time. This study provides a basis for the use of VST in large scale sampling of G. morsitans to determine its geographical limit, a critical aspect in the planning of vector control strategies and interventions.

Monitoring the effectiveness of tsetse fly control interventions that aim to reduce transmission of African trypanosomiasis requires highly efficient sampling tools that can catch flies at low densities. The sticky small target (StS-target) has previously been shown to be more effective in sampling Glossina fuscipes fuscipes compared to the biconical trap. However, its efficiency in terms of the proportion of flies it catches out of those that visit it has not been reported. Furthermore, there are no reports on whether tsetse samples caught using the StS-target can be used for subsequent processes such as molecular tests. In this study, we evaluated the efficiency of the biconical trap and targets for sampling G. f. fuscipes. All targets were tiny (0.25 × 0.50 m) but varied in their capture system. We used targets with sticky surface (StS-targets) and those with an electrified surface (ES-targets). We also assessed the suitability of flies caught on the StS-target for molecular tests by amplifying DNA of bacterial communities. Randomized block design experiments were undertaken in Mbita area and Manga Island on Lake Victoria of western Kenya. Fly catches of each sampling tool were compared to those of the sampling tool flanked by electric (E) nets and analyzed using a negative binomial regression. The total catch for each sampling tool alone was divided by the total catch of the sampling tool flanked by two E-nets to obtain its efficiency expressed as a percentage. A proportion of flies caught on the StS-target was preserved for molecular tests. Overall, the efficiencies of the biconical trap, ES-target and StS-target were 7.7%, 13.3% and 27.0%, respectively. A higher proportion of females (69 to 79%) than males approached all the sampling tools, but the trap efficiency was greater for male G. f. fuscipes than females. Furthermore, sequencing the 16S rRNA gene from fly samples caught on the StS-target revealed the presence of Spiroplasma. Our results indicate that the SS-target is the most efficient trap to monitor G. f. fuscipes population during interventions, with the biconical trap being the least efficient, and samples collected from StS-targets are suitable for molecular studies.

Background Small targets comprising panels of blue and insecticide-treated black netting material each 0.25 × 0.25 m have been shown to attract and kill Glossina fuscipes fuscipes Newstead, 1910 (Diptera: Glossinidae) thereby reducing its population density by over 90% in field trials. However, their attractive ability has not been fully exploited for sampling purposes. Therefore, in this study we assessed the effectiveness of using sticky small targets as sampling tools for G. f. fuscipes in western Kenya. We also determined the influence of colour on the landing response of female and male flies on sticky small targets. Methods Using a series of randomised block experiments, the numbers of tsetse flies caught with sticky small targets were compared with those caught with biconical traps. A negative binomial regression was used to model fly catches. Odds ratios as measures of association between the landing response on the blue or black panel of the sticky small target and the sex of flies were obtained from a multiple logistic regression. Results The results showed that sticky small targets caught 13.5 and 3.6 times more female and male tsetse flies than biconical traps (Z = 9.551, P < 0.0001 and Z = 5.978, P < 0.0001, respectively). Females had a 1.7 times likelihood of landing on the black panel than males (Z = 2.25, P = 0.025). Conclusion This study suggests that sticky small targets are an effective sampling tool for G. f. fuscipes. Therefore, we recommend the use of sticky small targets as an alternative to biconical traps for observational and experimental investigations of G. f. fuscipes.

Tsetse flies (Diptera: Glossinidae) are considered primary cyclical vectors that transmit pathogenic trypanosomes in Africa. They harbour a variety of microbes including Wolbachia, Sodalis and the salivary gland hypertrophy virus (SGHV) which are all vertically transmitted. Knowledge on tsetse microbiome and their interactions may identify novel strategies for tsetse fly and trypanosomiasis control. Area-wide application of such strategies requires an understanding of the natural microbiome frequency in the different species and subspecies of Glossina in their geographical populations. Consequently, this study determined the prevalence of Sodalis, Wolbachia, SGHV and trypanosome infections in Glossina morsitanscentralis from two sites of Western Zambia. We also explored possible associations of the microbes with trypanosome infections. Male G. morsitanscentralis samples were collected from two sites (Lyoni and Lusinina) in Western Zambia. The age structure of the flies at each site was determined using the wing fray method. DNA was extracted from the samples and analyzed for Wolbachia, Sodalis, SGHV and trypanosome presence using PCR. Associations and measures of associations between trypanosome infection and microbes in the fly were determined. The flies from the two locations (Lusinina, n=45 and Lyoni, n=24) had a similar age structure with their median fray category not being significantly different (p=0.698). The overall prevalence of Wolbachia was 72.5% (95% CI: 61.6-83.3%), Sodalis was 15.9% (95% CI: 7.1-24.8%), SGHV was 31.9% (95% CI: 20.6-43.2%) and Trypanosoma species was 23.2% (95% CI: 13-33.4%). The prevalence of Wolbachia was significantly higher in Lusinina than Lyoni (p=0.000). However this was not the case for Sodalis, SGHV and Trypanosoma species. Despite the low number of flies that were positive for both trypanosome and Sodalis (6; 8.7%), a statistically significant association (p=0.013; AOR 6.2; 95% CI: 1.5-25.8) was observed in G. morsitanscentralis. The study showed that the prevalence of microbiota may vary within the same species of the tsetse depending on the geographical location as was the case of Wolbachia. Further it showed that infection with Sodalis could affect vector competence. The study concludes that Sodalis could be an ideal candidate for symbiont-mediated trypanosomiasis control interventions in G. morsitanscentralis.

Trypanocides will continue to play an important role in the control of tsetse fly transmitted trypanosomosis now and in the near future. The drugs are mostly administered by farmers without any veterinary supervision leading to misuse and under dosing of medication, and these could be factors that promote trypanocidal drug resistance (TDR) development. In order to delay or prevent TDR, the Food and Agriculture Organization (FAO) recommended guidelines on trypanocide use. It is not known if these recommended guidelines are adhered to in Itezhi tezhi district of Zambia. A survey was undertaken to examine how socio-economic and environmental factors were associated with adherence to the recommended guidelines on trypanocide use in Itezhi tezhi, Central Zambia. Ninety farmers who use trypanocides were interviewed using a questionnaire to collect their socio-economic characteristics (age, education in years, cattle herd size, competence on trypanocide use and their access to extension on trypanocide use) and trypanocide usage practices while crush pens which they use were stratified according to location, whether in the Game Management Area (GMA) (Mutenda, Itumbi, Kapulwe and Banachoongo) or non-GMA (Iyanda, New Ngoma and Shinampamba) as an environmental factor. Associations and measures of associations to adherence of FAO guidelines were determined. The results showed that 25.6% of the farmers adhered to guidelines by FAO on trypanocide use and that none of the socio-economic factors under investigation were significantly associated with it. Further the farmers that used crush pens that were in the GMA had an 80% reduction in the likelihood of adhering to the FAO guidelines on trypanocide use than those that used crush pens in the non-GMA (AOR 0.20, 95% CI: 0.05–0.81, P = 0.02). There was low adherence to the recommended FAO guidelines on trypanocide use and it was associated with the location of the crush pen whether in the GMA or not, as an environmental factor. With farmers in the GMA less likely to adhere to FAO guidelines than those in the non-GMA, we recommend an integrated approach of measures to control trypanosomosis in the GMA of Itezhi tezhi to lessen overuse of trypanocides by the farmers.

Background The measure of anaemia status using packed cell volume (PCV) can be a reliable indicator of African trypanosomosis (AT) in the absence of other anaemia-causing conditions. However, studies that have estimated prevalence of anaemia in cattle from AT endemic areas have rarely reported the prevalence of the disease in the anaemic cattle. Therefore we investigated the prevalence of AT in anaemic cattle at sites that had recently reported the disease in Itezhi tezhi district of central Zambia. Methods During a survey, blood samples were collected from 564 randomly selected cattle for anaemia determination from seven crush pens (Mutenda, Kapulwe, Banachoongo, Itumbi, Iyanda, New Ngoma and Shinampamba). At a PCV- value cut off of 26 %, all samples positive for anaemia were subjected to both parasitological examination on thick and thin blood smears and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for detection of trypanosome DNA. Fisher’s exact test and a mixed effect logistic regression analyses were used to determine and measures associations, respectively. Results Of 564 cattle screened, 58 (10.3 %; 95 % CI: 7.8–12.8 %) had anaemia. PCR-RFLP results showed that 17 (29.3 %; 95 % CI; 17.2–41.4 %) anaemic cattle were positive for pathogenic trypanosomes compared to 1 (1.7 %; 95 % CI: 0.0–5.2 %) on parasitological examination using thick smears. The infections were caused by Trypanosoma congolense and Trypanosoma vivax. Fisher’s exact test showed a strong association between PCV and pathogenic trypanosome infection (P = 0.004). A mixed effect multivariate logistic regression showed that a one unit increase in PCV reduced the likelihood of detecting AT with PCR-RFLP by 24.7 % (95 % CI: 4.6–40.6 %; P = 0.019) in anaemic cattle, taking into account their age and sex, with random effects for crush pen. Conclusion These results suggest that T. congolense and T. vivax could be important causes of anaemia in cattle reared in AT endemic areas of Itezhi tezhi in Central Zambia. This also suggests that even though pathogenic trypanosomal infection was strongly associated with PCV, it could only account for up to 41 % of the anaemia in cattle. Therefore further investigation to ascertain other factors responsible for anaemia in AT endemic areas of Itezhi tezhi in Central Zambia is needed.